Advertisements inserted into online videos have become ubiquitous. But is anyone watching them? Given that viewers often have the option to watch for a few seconds then skip to video, advertisers may be missing out their fair share of eyeballs.

How effective are video ads? This was the question posed by researchers at the University of Massachusetts earlier this year. The results, summarized by Print in the Mix, show some interesting trends:

1. Videos that are inserted in the middle of the content got the most user engagement, with 97% of viewers “completing” the ad viewing, compared to 74% at the beginning and just 45% at the end. In fact, of all the variables studied, the position where the ad was inserted had the biggest impact on engagement.

2. Repeat site visitors completed viewing the ads more frequently than one-time visitors. The researchers suggest that “Repeat visitors are likely more interested in the videos offered by that site than one-time visitors, and hence more willing to watch the ads.”

3. Ads in long-form content were viewed more often than in short-form, suggesting viewers of the longer content held it in higher esteem and were more willing to “pay” for it by watching an ad.

4. What we found most interesting is the fact that viewers were far more patient with ads than with slow-loading videos.

“One set of viewers experienced a slow-to-load video, while another set watched a pre-roll ad that must complete before the video begins. While both sets of viewers were waiting to watch their chosen video, the viewers watching the slow-to-load video abandoned more than three times faster as the other group,” according to the article.